Delayed weed removal is the primary cause of maize yield
loss in smallholder agriculture. The slog for weed management could probably be
reduced if the initial weed control removal is restricted to the in-row weeds,
followed soon after by elimation of inter-row weeds before competition sets in.
This strategy would most likely minimise the competitive effect of both intra-row
and inter-row weed infestations. However, the width of the area that must be weeded
along the crop row and the timing of the subsequent inter-row weeding are largely
unknown. Experiments were carried out in 1993/94 rainy season under controlled
conditions to assess the area of influence of
Eleusine indica
(L.) Gaertn (
Rapoko grass) on maize. The study was also carried out under
field conditions during the 1994/95 and 1995/96 rainy seasons, and in addition
to weed width to be removed, the timing of the subsequent inter-row weeding was
also studied. While
E. indica plants spaced 40 cm were as effective as
those closer to the maize row in reducing grain yields under controlled conditions,
grain yield reduction was significantly (P<0.05) less under field conditions.
Furthermore, results of both seasons suggest that inter-row weeds must be removed
by four weeks after crop emergence to avoid maize grain yield reduction.
